Self-lowering jack



J. C. KOPF.

SELF LOWERING JACK.

APPLICATION FILED FEB. 4, 1921.

1,397,868, Patented Nov. 22, 1921.

4 SHEETS-SHEET I.

J. C. KOPF.

SELF LOWERING JACK.

APPLICATION FILED FEB. 4, 1921.

1,397,868. Patented Nov. 22, 1921.

4 SHEETS$HEET 2.

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amvmtoz 554 c. 71 2 M2 attovwc J. C. KOPF.

SELF LOWERiNG'JACK.

APPLICATION FILED FEB. 4. 1921.

1,397, Patented Nov. 22, 1921.

4 SHEETS-SHEET 3.

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J. C. KOPF.

SELF LOWERING JACK.

APPLICATION FILED FEB. 4. I921.

1,397,868. Patented Nov. 22, 1921.

57 5 4 SHEETS-SHEET 4.

12 WWW7 UNITED STATES PATENT OFFICE.

JOHN C. KOPF, OF BELLEVUE BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE DUFF MANUFACTURING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A. CORPORATION OF PENNSYLVANIA.

SELF-LOWERING JACK.

Application filed February 4, 1921.

To (ZZZ whom it may concern Be it known that I, JOHN C. Kerr, a citizen of the United States-and a resident of the borough of Bellevue. in the county of Allegheny and State of Pennsylvania, have invented a new and useful Self-Lowering Jack, of which the following is a specification.

The object of the invention is to provide a self-lowering screw-jack of simple and advantageous mechanism, whereby dangerous speeds and shocks in lowering are avoided.

In the accompanying drawings, forming a part hereof:

Figure 1 is a vertical section through a jack embodying the invention, taken in the axial plane of the screw and main operating shaft, which are shown in elevation;

Fig. 2 is an enlarged vertical section on the line 22 of Fig. 1, with the bladed members of the liquid-retarding device partly in section and partly in elevation;

Fig. 3 is a fragmentary view showing the right-hand portion of Fig. 2 with the casing in vertical section and interior parts in elevation;

Fig. 1 is a face view of one of the rotary members of the liquid-retarding device;

Fig. 5 is an edge view of said member, with a portion broken away and in section:

Fig. 6 is a vertical section on the line 6-6 of Fig. 2;

Fig. 7 is a face view of one of the stationary members of the liquid-retarding device; and

Fig. 8 is an edge view of said member, with a portion broken away and in section.

The .jack has a base 1, provided with a hollow standard 2 and an annex chamber 3 toward the bottom. The vertically movable load member is preferably in the form of a ram 4 slidably guided in a bearing 5 in the top of the stationary standard of the base, the top of the ram having a head 6 to act upward against the jacking point of the part to be raised. The ram is held against turning by a key 7 held in the upper part of the standard and projecting into a vertical groove 8 in the side of the ram.

The ram is hollow and its lower portion holds, or is formed as, a nut 9, or non-rotary screw member. A male screw 10 is support-ed rotatably on the base upon a ba1l- Patented Nov. 22, 1921.

Serial No. 442,366.

bearing 11, and passes upward through the nut into the interior of the ram.

The screw 10 is rotated to effect lifting through a horizontal main operating shaft 12 journaled in bearings 13 and 1 1 in the outer and inner portions of the annex, and having on its inner end a bevel pinion 15 which meshes with a larger bevel gear 16 fixed on the lower portion of the rotary screw member. The projecting outer end of the operating shaft carries a customary ratchet lever device 17, whereby rotary movement of the screw in one direction, the lifting direction, is produced by oscillatory movement of a removable bar.

The threads of the screw, meaning thereby the two screw members, are to be understood as being of steep pitch, that is to say, beyond the angle of repose, so that the jack will run down by itself under load, if not held. At such time, through the relative vertical movement of the rotary and nonrotary screw members, the screw 10 is rotated by the load in the direction reverse to that of lifting, and this in turn rotates the shaft 12 in the run-down or lowering direction.

An auxiliary shaft 18, for holding and lowering, is journaled in bearings 19, 20 in the annex chamber, transversely to the main operating shaft; and fixed on this shaft and held against longitudinal movement by the bearings is a worm 21, which meshes with a worm-wheel 22 fixed to the main shaft. The worm-wheel and worm are also of comparatively steep pitch, so that the worm will be rotated by the worm-wheel.

The invention includes a closed rotary liquid-retarding device, marked generally 23, which is shown housed in a barrel 24 forming an extension of the annex chamber 3. The said barrel is preferably provided with an enlarged inner portion 25, which is bolted or otherwise separably secured to the main body of the annex casing. As thus constructed, a rotary brake-drum member 26 is rim-journaled, coaxial with the shaft 18, in a bearing-ring 27 inserted in the enlargement 25, and in a bearing 28 in the mouth of the annex body, between which bearings it is held against axial displacement. A circular series of ratchet teeth 29 on this member, and a collar 30 with cooperative teeth, slidably keyed to the end blades 49 are reversely inclined.

of the shaft 18 and pressed by a spring 31, constitute an embodiment of one-way-acting clutch Or connection.

The drum is encircled by a brake-band 32, having perforated end lugs 33, which are suspended on a rod 34 having bearings in openings in the top of the annex, one of the end portions of the rod being a thrust screw 35 engaging cooperative threads in the wall, whereby the brake can be released and tightened by manipulation of an external lever handle 36 on the screw, a spring 37 tending to open the band when the screw is backed off. i

The innerend of the barrel 2a is tightly closed by a bolted head 38 and interposed packing 39, and said head and the outer fixed head are formed with openings and packing glands 40, 41. Through these glandspasses a rotary rod or shaft member 4-2, which is screwed into the drum 26, co axial therewith. WVithin the barrel are rotary and fixed bladed members 43, 4A, of suitable number. In the illustrated construction there are two of each, the members alternating. The rotary members are formed with rims 45 adapted to turn within the barrel, and hubs 46 having slots 1-7 whereby they are seated upon the shaft 42 in engagement with driving keys 48 therein. A multiplicity of generally radiating, some what tangential blades 49, transversely inclined after the manner of a turbine, connect the hub and rim. The stationary members are similar, except that the rims 45 are slightly larger to fit the barrel snugly, that the hubs 46 are of larger internal diameter so as to clear the keys 48, and that the The stationary members are held against turning by set-screws 50. The entire interior of the closed device not occupied by the parts is filled with a liquid 51, which may be more or less viscous. The holding and lowering means, with the exception of the brake-band and handle, can be removed by simply unbolting the drum section of the casing from the annex.

In operation, the load is lifted in the usual way, by ratcheting the shaft 12. In this operation the teeth of the member 30 of the automatic clutch ride idly over the teeth on the drum 26, the-drum and the rotary part of the device 23 remaining stationary. At the end of each stroke the effort of the load transmitted and reduced through the gearing and tending to rotate the member 26 in the reverse direction, causes the clutch to catch, and is thereby solidly sustained by the brake, which remains applied during lifting. In order to effect lowering the brake-band is loosened by vmeans of the handle 36, thus permitting the drum to turn, whereupon the load member 4 7 starts to descend. Thereby, through. the screw memhers, multiplying gears 16, 15, 22, and 21, and the clutch, the rotary bladed members 43 are rotated in and against the confined liquid and relatively to the stationary memhere 44, whereby, owing to the eddy currents or partly to the viscosity of the liquid, a continuous yielding resistance is offered, which is effective to prevent the jack running away, or from attaining such speed that the results will be injurious when the brake is again applied to stop the load.

What I claim as new is:

1. In a self-lowering jack, a base and a vertically movable load member, vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, manually releasable means automatically operative to hold the load member, and a closed rotary liquidretarding device operatively connected with the screw.

2. In a self-lowering jack, a base and a vertically movable load member, vertical screw 'means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, manually releasable means automatically operative to hold the load member, and a retarding device comprising a closed casing-containing a body of liquidand rotary and stationary bladed members therein, the rotary members being operatively connected with the screw.

3. In a self-lowering jack, a base and a vertically movable load member, vertical screw means forlifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, manually releasable means automatically operative to.

hold the load member, a closed rotary liquidretarding device, multiplying gearing and a one-way-acting clutch between said device andthe screw.

ll In a self-lowering jack, a base and a vertically movable load member, vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, an auxiliary shaft geared to said screw, a manually-releasable holding device and a closed rotary liquid-retarding device coaxial with said shaft.

5. In a self1owering jack, a base and a vertically movable load member, vertical screw means for lifting comprising a screw which. is rotatedin one direction to effect lifting and in the opposite direction by the action of'the load in lowering, a main operating shaft geared to said screw and bearing a worm-wheel, an auxiliary shaft bearing a worm meshing said worm-wheel and adapted to be driven thereby, a closed rotary liquid-retarding device and a manually-coir trolled holding device, together with a onewayacting connection, all coaxial with said auxiliary shaft.

6. In a self-lowering jack, a base and a vertically movable load member, .vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, an auxiliary shaft geared to Said screw a rotary member coaxial with said shaft, a one-way-acting connection between said shaft and rotary member, a manual brake cooperative with said rotary member, and a closed rotary liquid-retarding device directly connected with the rotary member.

7. In a self-lowering jack, a base and a vertically movable load member, vertical screw means for lifting comprising a screw which is rotated in one direction to effect lifting and in the opposite direction by the action of the load in lowering, an auxiliary shaft geared to the screw a detachable barrel coaxial with said shaft, and a rotary liquid-retardingdevice contained in said barrel in operative relation to said shaft.

JOHN C. KOPF. 

